1. Field of the Invention
The present invention relates to a spectacle lens, which is designed and manufactured taking into consideration the distance between the center of rotation of the eye and a spectacle lens of an individual spectacles wearer, and a manufacturing method therefor.
2. Description of the Related Art
Despite the fact that spectacle lenses comprises single vision lenses and multifocal lenses (including progressive-power lenses) with different optical characteristics, they are generally designed on the basis of certain average utilization conditions. An example in which individual utilization conditions are taken into consideration is the method disclosed in Japanese Patent Application Laid-open No. 6-18823, in which there is proposed a progressive-power lens designed in consideration of individual utilization conditions, and there is disclosed the use of an aspheric surface, which is not accompanied by point symmetry axial symmetry in a prescription surface. The term “utilization conditions” as used here refers to the distance between the back surface of a spectacle lens (the surface of the eye side) and the vertex of the cornea, the tilt f the frame, and so forth, and an attempt is made to optimize a prescription surface by using these data in lens design.
However, the technique disclosed in the above-mentioned publication has an object to optimize a progressive-power lens comprising a distance portion, a near portion, and an intermediate portion, and having a prescription surface for both far and near vision use, and in particular, takes into consideration the importance of utilization conditions in the case of a spectacle lens, like a progressive-power lens, having a prescription, which supplements the accommodative power in near vision for presbyopia. This is because a progressive-power lens requires particularly accurate adjustment of s determining the conditions of a corrective prescription, is deemed particularly necessary. Therefore, the disclosure in the publication only emphasizes the accurateness of a near use prescription, and does not address overall wearing conditions for lenses such as spherical design lenses, aspherical single vision lenses, and bifocal lenses.
The present invention was devised based on the above-mentioned circumstances, and has as an object to provide a spectacle lens and a manufacturing method thereof, having a prescription surface which has been further optimized by reviewing the wearing conditions for all spectacle lenses, which was not paid much attention to in the past, and by taking into consideration individual wearing conditions.